Gene editing used to produce babies from two female mice

In what marks a major breakthrough in genetic research, scientists have a produced healthy mice pups from two female mice.

Researchers from the Chinese Academy of Sciences were able to produce healthy mice from both two mothers, and two fathers – although the pups from the two males only survived a few days.

Professor Qi Zhou, co-senior author of the study, said: “We were interested in the question of why mammals can only undergo sexual reproduction.

“We have made several findings in the past by combining reproduction and regeneration, so we tried to find out whether more normal mice with two female parents, or even mice with two male parents, could be produced using haploid embryonic stem cells with gene deletions.”

While other classes of animals – including reptiles, amphibians, and fish – can reproduce with one parent of the same sex, mammals struggle to do the same.

In mammals, certain genes are shut off as the cells form, due to a mechanism called ‘genomic imprinting’.

This means that some offspring don’t receive genetic material from both the mother and father – leading to development issues.

By deleting these imprinted genes from immature eggs, researchers have previously been able to produce mice from two females – however, they still have defective features.

In the new study, the researchers used haploid embryonic stem cells (ESCs) – cells from embryos that can develop into any type of cell, which contained half the normal number of chromosomes and DNA from only one female parent.

They then deleted three imprinting regions in these haploid ESCs, before injecting them into eggs from another female mouse.

Incredibly, the two mice produced 29 live mice, which were normal, lived to adulthood and even had babies of their own.

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Baoyang Hu, co-senior author of the study, said: “We found in this study that haploid ESCs were more similar to primordial germ cells, the precursors of eggs and sperm. The genomic imprinting that’s found in gametes was ‘erased’.”

The team also attempted to produce babies from two fathers, but the pups produced only survived a few days, as the team had to delete seven key imprinted regions.

While the team notes that there are obstacles to overcome before these methods could be used in other mammals, they hope to explore these techniques in the future.

Professor Li added: “This research shows us what’s possible.”

However, other researchers doubt that the technique could ever be used in humans.

Dr Dusko Ilic, Reader in Stem Cell Science at King’s College London, said: "To consider exploring similar technology for human application in the near future is implausible.

"The risks of severe abnormalities is too high, and it would take years of research in various animal models to fully understand how this could be done safely."